Room temperature fast curable organopolysiloxane compositions of the condensation curing type known in the art include compositions of one part type comprising a both end hydroxy-terminated organopolysiloxane as a base polymer and a crosslinking agent in an amount minimized so as to increase the crosslinking rate through hydrolysis, and compositions of two part type wherein a both end hydroxy-terminated organopolysiloxane as a base polymer and a crosslinking agent are separately packed.
The compositions of one part type, however, are not regarded as fast curing since they merely have a high curing rate from the surface and require a certain time for deep curing. By contrast, the compositions of two part type are relatively fast in depth curing, but are difficult to handle on account of a mixing ratio of the two parts departing from 1:1 and thus inapplicable to an automatic mixing dispenser. In order to drive complete curing to depths, the quantity of hydroxyl at both ends of organopolysiloxane or polyoxyalkylene polymer and the quantity of crosslinking agent added must be strictly controlled, or water must be further added as a deep curing agent.
On the other hand, organopolysiloxane compositions of the addition curing type are efficient to work with since the two parts are mixed in a ratio of 1:1. However, the working environment is limited since a heating oven is generally necessary for curing and the curing catalyst can be poisoned in the presence of an addition poison.
To solve these problems, we proposed in U.S. Pat. No. 5,319,050 a composition comprising a diorganopolysiloxane blocked with a hydrolyzable silyl group at either end of its molecular chain, 0.001 to 1 mol of an organic compound having at least one C.dbd.O group in a molecule, and 0.001 to 1 mol of an organic compound having at least one NH.sub.2 group in a molecule. This is a room temperature fast curable organopolysiloxane composition which utilizes water formed as a by-product by ketimine forming reaction between C.dbd.O and NH.sub.2 groups. Continuing investigations, we found that when the diorganopolysiloxane as the base polymer is end-blocked with a hydrolyzable silyl group, the composition maintains storage stability etc., but its fast curing property does not significantly exceed that of conventional well-known two part type compositions wherein a both end hydroxy-terminated organopolysiloxane and a crosslinking agent are separately packed.
JP-A 61-204289 discloses a humidity-curable sealing composition comprising a polyoxyalkylene ether backbone polymer having a hydrolyzable silicon group at an end of its molecular chain and the reaction product between an amine compound and a carbonyl compound with water removed. Since water has been removed from the reaction product, the composition cannot be fast curing.